diff --git a/gamemodes/zombiesurvival/gamemode/init.lua b/gamemodes/zombiesurvival/gamemode/init.lua
index 751e434..9037456 100644
--- a/gamemodes/zombiesurvival/gamemode/init.lua
+++ b/gamemodes/zombiesurvival/gamemode/init.lua
@@ -82,6 +82,8 @@ AddCSLuaFile("vgui/zshealtharea.lua")
 AddCSLuaFile("vgui/zsstatusarea.lua")
 AddCSLuaFile("vgui/zsgamestate.lua")
 
+include("multithread.lua")
+
 include("sh_globals.lua")
 
 include("obj_entity_extend_sv.lua")
diff --git a/gamemodes/zombiesurvival/gamemode/multithread.lua b/gamemodes/zombiesurvival/gamemode/multithread.lua
new file mode 100644
index 0000000..a279157
--- /dev/null
+++ b/gamemodes/zombiesurvival/gamemode/multithread.lua
@@ -0,0 +1,53 @@
+require("effil")
+
+GM.MT = {}
+local m = GM.MT
+
+local charset = {}
+
+for i = 48,  57 do table.insert(charset, string.char(i)) end
+for i = 65,  90 do table.insert(charset, string.char(i)) end
+for i = 97, 122 do table.insert(charset, string.char(i)) end
+
+function randStr(length)
+  math.randomseed(os.time())
+
+  if length > 0 then
+    return randomStr(length - 1) .. charset[math.random(1, #charset)]
+  else
+    return ""
+  end
+end
+
+function m:WaitForAll(threads)
+    local results = {}
+    for i=1, #threads do
+        results[i] = threads[i]:get()
+    end
+    return results
+end
+
+function m:MarkEntity(ent)
+    if not ent or not ent:IsValid() then return nil end
+    ent._MT_ID = ent._MT_ID or randStr(5)
+    return {ent:GetClass(), ent._MT_ID}
+end
+
+function m:FindEnt(id)
+    if not id then return nil end
+    for _,v in pairs(ents.FindByClass(id[1])) do
+        if v._MT_ID == id[2] then return v end
+    end
+    return nil
+end
+
+hook.Add("PlayerSpawn", "aa", function(ply)
+    effil.thread(function()print("we are on the other thread")end)()
+    local id = GAMEMODE.MT.MarkEntity(ply)
+    PrintTable(id)
+    print("main")
+    --[[effil.thread(function(t)
+        local p = GAMEMODE.MT.FindEnt(t)
+        print("t p", p)
+    end)]]
+end)
\ No newline at end of file
diff --git a/readme.md b/readme.md
index 4f0553b..c6762b6 100644
--- a/readme.md
+++ b/readme.md
@@ -1,5 +1,7 @@
 English | [中文（简体）](readme_zh-CN.md)
 
+**WARNING: This edition of Zombie Survival requires extra library on server.**
+
 # Zombie Survival
 The definitive zombie experience.
 A gamemode for Garry's Mod.